Indeterminate Kidney Lesion
An indeterminate kidney lesion is a finding on imaging where a mass, cyst, or abnormality in the kidney cannot be confidently classified as benign or malignant. These lesions may represent a simple cyst, a complex cyst, a benign tumor, inflammation, infection, or a kidney cancer. Because the imaging features are unclear or incomplete, further evaluation or follow-up is often needed to determine the true nature of the lesion.
What is it?
An indeterminate kidney lesion means that a renal abnormality does not show enough clear imaging features to classify it confidently. Some lesions appear partially solid, partially cystic, or show subtle enhancement that requires closer evaluation. Benign possibilities include simple cysts, hemorrhagic cysts, or angiomyolipomas. More concerning possibilities include renal cell carcinoma or complex cystic tumors.
Imaging—especially contrast-enhanced CT or MRI—helps evaluate the lesion’s internal structure, enhancement patterns, and borders. Additional imaging or a short-term follow-up scan may be recommended if the lesion is too small or too subtle to characterize with certainty.
Important to Know
Many indeterminate kidney lesions are small and turn out to be benign. Features such as size, enhancement, calcifications, and internal complexity help guide next steps. When imaging suggests a higher-risk lesion, timely follow-up or biopsy may be recommended to ensure early detection of any serious condition.
Red flag symptoms include persistent flank pain, blood in the urine, unexplained weight loss, fever, or night sweats. These may indicate infection, inflammation, or a more serious underlying lesion and warrant prompt evaluation. Follow-up imaging is often essential to confirm stability or progression.